The Rubin Users Committee (UC) thanks the Rubin Project members for their continued efforts in serving the user community during the early science optimization phase of the LSST. The committee congratulates the Observatory on the start of alert production in the Deep Drilling Fields and on the discovery of over thousands of new asteroids. The committee also wishes to report feedback on the outstanding support provided by the Rubin science team and Data Management liaison to the Solar System Science Collaboration (SSSC) during the Solar System sprint in February, as well as the prompt release of 3I/ATLAS observations with cutouts and an example notebook. These were not planned deliverables given the current state of operations, and the community deeply appreciates the effort.
Finding 1: Solar System Data Access and the Prompt Products Database
The SSSC and the broader Solar System community face significant challenges in accessing Rubin Solar System data products during the current early science optimization phase, resulting in potential lost scientific opportunities. Rubin has discovered over 11,000 new asteroids and detected more than 80,000 known Solar System small bodies, but this data is not currently served through any alert broker, nor is it accessible on the RSP. The relevant astrometry and photometry has been submitted to the Minor Planet Center (MPC), but crucial metadata are missing. The alert structure has also changed: Solar System object association in alerts now relies on MPC confirmation rather than direct pipeline association, meaning the community must await MPC verification before objects are reliably identified. This leads to duplicated effort and inconsistent approaches across groups. The current Solar System processing pipeline computes orbital and geometric quantities, including heliocentric and topocentric distances and phase angles, that are not yet publicly accessible through the RSP, even though they are already being produced. In the interim, the SSSC has been constructing a community database augmented with these quantities with support from the B612 Foundation, but this workaround is unsustainable as data rates increase and places an undue burden on a small number of groups who are effectively providing a service to the entire community.
The committee recognizes the complexity of the current situation, including the fact that some of this processing occurs outside the standard documented pipeline. The committee encourages the Observatory to explore mechanisms to make Solar System processing pipeline outputs more accessible to the RSP user community as a stopgap measure until the Prompt Products Database (PPDB) is delivered. Rubin Solar System data products are small relative to the full astrophysical transient data volume, and bridging this gap would substantially expand scientific return during the early science optimization phase.
Finding 2: Access to Pointing History and Survey Footprint Information
Community access to the pointing history of the telescope and associated metadata would significantly benefit a broad range of science cases. The scientific motivation spans multiple collaborations that rely on time-domain data. The committee notes that the Rubin scheduler now provides observation timing information in the nightly summaries, in addition to field identifiers, which was a much needed feature. It would be desired to have further information available, such as limiting magnitudes and seeing, and an easy way to grab the information.
The committee is aware that a file covering December through April is expected to be released through the RSP around July 2026. The committee recommends that the Observatory communicate clearly to the community the planned timeline, content, and format of this release, and considers additional columns to be of high scientific value across multiple communities. The committee encourages the Observatory to provide this information at regular intervals consistent with the approach used during Science Validation.
Finding 3: Discoverability of In-Kind Contributions
The committee continues to hear from users who have difficulty identifying, locating, and accessing resources contributed through Rubin’s in-kind partner programs. While a dedicated webpage exists at https://in-kind-program.lsst.io/ and platforms such as IDACs are intended to host contributed datasets, users report that it is not straightforward to determine what has been delivered, what is still forthcoming, or how to access specific tools and data.
The committee understands that an improved website is in progress and acknowledges the work underway by the in-kind program team. The committee gently encourages the Observatory to continue prioritizing discoverability improvements, and suggests that a brief community-facing communication highlighting what is currently available and how to access it would be of immediate benefit.
Finding 4: Template Generation: Transparency and Community Engagement
The community has expressed ongoing confusion about the current plans for template generation, particularly for sky regions outside the Deep Drilling Fields. This uncertainty significantly hinders science cases that depend on image differencing, including transient, variable star, and Solar System science, and makes it difficult for community members to plan follow-up programs or assess the suitability of Rubin data for their ongoing programs. The committee is aware of ongoing discussions with Rubin leadership on this topic and acknowledges that Eric Bellm recently provided new information via Community Forum, which was well received.
The committee encourages the Observatory to be more transparent and proactive in communicating the template generation strategy and timeline to the community. There is substantial expertise within the Science Collaborations that could inform decisions about template quality and generation processes, and the committee encourages the Observatory to engage the community in this discussion. A technical note documenting how image subtraction quality depends on the number of input template images, along with the metrics used to evaluate that quality, would be of significant value to the community in understanding what science is currently feasible and what will become possible as operations mature.
Finding 5: Timestamps in Observation Logs and Documentation
The committee reiterates its recommendation, supported broadly across the community, that timestamps and version indicators be added to all documentation pages and observation logs. Users continue to report difficulty determining when documentation was last updated and which data release it corresponds to, and the absence of observation timestamps limits the utility of pointing history data for time-sensitive science. The committee strongly encourages the Project to treat this as a priority.